Texas Instruments INA231EVM User manual

User’s Guide
INA231EVM (Rev A)
ABSTRACT
This user's guide describes the characteristics, operation, and use of the INA231EVM evaluation board (Rev
A) hardware. This document discusses how to set up and configure the software and hardware, and reviews
the program operation. Throughout this document, the terms evaluation board, evaluation module, and EVM are
synonymous with the INA231EVM. This user's guide also includes information regarding operating procedures,
the input and output connections, an electrical schematic, printed circuit board (PCB) layout drawings, and a
parts list for the EVM.
Table of Contents
1 Overview..................................................................................................................................................................................2
1.1 INA231EVM Kit Contents...................................................................................................................................................2
1.2 Related Documentation from Texas Instruments............................................................................................................... 3
2 INA231EVM Hardware............................................................................................................................................................ 4
2.1 Theory of Operation for INA231 Hardware........................................................................................................................ 4
2.2 Signal Definitions of H1 (10-Pin Connector Socket).......................................................................................................... 5
3 INA231EVM (Rev A) Hardware Setup....................................................................................................................................6
3.1 Electrostatic Discharge Warning........................................................................................................................................ 6
3.2 Connecting the Hardware.................................................................................................................................................. 6
3.3 Connecting Power..............................................................................................................................................................6
3.4 Connecting the USB Cable to the SM-USB-DIG Platform................................................................................................. 7
3.5 INA231EVM Default Jumper Settings................................................................................................................................ 8
3.6 INA231EVM Features........................................................................................................................................................ 9
4 INA231EVM Software Setup.................................................................................................................................................11
4.1 Operating Systems for the INA231EVM Software............................................................................................................11
4.2 Software Installation......................................................................................................................................................... 11
5 INA231EVM Software Overview...........................................................................................................................................13
5.1 Starting the INA231EVM Software...................................................................................................................................13
5.2 Configuring the INA231EVM Software.............................................................................................................................14
5.3 Using the INA231EVM Software...................................................................................................................................... 18
6 INA231EVM Documentation.................................................................................................................................................21
6.1 Schematic........................................................................................................................................................................ 22
6.2 PCB Layout...................................................................................................................................................................... 23
6.3 Bill of Materials.................................................................................................................................................................24
7 Revision History................................................................................................................................................................... 27
Trademarks
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All trademarks are the property of their respective owners.
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1 Overview
The INA231 is a high-side current sensor and power monitor with an I2C interface. The INA231 monitors both
current and supply voltage, with programmable conversion times and averaging modes. The INA231EVM is a
platform used to evaluate the performance of the INA231 under various signal, shunt, and supply conditions.
This document gives a general overview of the INA231EVM and provides a general description of the features
and functions to consider when using this evaluation module.
1.1 INA231EVM Kit Contents
Table 1-1 summarizes the contents of the INA231EVM kit. Figure 1-1 shows all of the included hardware.
Contact the Texas Instruments customer support center if any component is missing.
TI recommends users check the INA231 product folder on the TI website at www.ti.com to verify that they have
the latest versions of the related software.
Table 1-1. INA231EVM Kit Contents
ITEM QUANTITY
INA231EVM PCB Test Board 1
SM-USB-DIG Platform PCB 1
USB Extender Cable 1
SM-USB-DIG Connector Ribbon Cable 1
User’s Guide CD-ROM 1
Figure 1-1. Hardware Included with INA231EVM Kit
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1.2 Related Documentation from Texas Instruments
The following documents provide information regarding Texas Instruments' integrated circuits used in the
assembly of the INA231EVM. This user's guide is available from the TI web site under literature number
SBOU128. Any letter appended to the literature number corresponds to the document revision that is current at
the time of the writing of this document. Newer revisions may be available from www.ti.com, or call the Texas
Instruments' Literature Response Center at [phone] or the Product Information Center at [phone].
When ordering, identify the document by both title and literature number.
Table 1-2. Related Documentation
DOCUMENT LITERATURE NUMBER
INA231 Product Data Sheet SBOS644
SM-USB-DIG Platform User
Guide
SBOU098
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2 INA231EVM Hardware
Figure 2-1 shows the overall system setup for the INA231EVM. The PC runs software that communicates
with the SM-USB-DIG Platform. The SM-USB-DIG Platform generates the analog and digital signals used to
communicate with the INA231 test board. Users can connect the INA231EVM test board to the system and
monitor the power, current, and voltage of the system under test conditions.
SM-USB-DIG INA231EVM
PC Shunt
Figure 2-1. INA231EVM Hardware Setup
2.1 Theory of Operation for INA231 Hardware
Figure 2-2 shows a block diagram of the INA231 test board hardware setup. The PCB provides connections
to the I2C interface and general-purpose inputs and outputs (GPIOs) on the SM-USB-DIG Platform board. The
PCB also provides connection points for external connections of the shunt voltage, bus voltage, and ground.
J1
10-Pin SM-USB-DIG Connector
INA231
Vdut Supply
(DVDD)
I C Interface
2
T3, T4
Shunt
Terminals
4J3, J4
J5, J6
I C Address Jumpers
2
A0
A1
Figure 2-2. INA231EVM Test Board Block Diagram
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2.2 Signal Definitions of H1 (10-Pin Connector Socket)
Table 2-1 lists the pinout for the 10-pin connector socket used to communicate between the INA231EVM and the
SM-USB-DIG. Note that the INA231EVM only uses the necessary I2C communication lines (pins 1 and 3) and
the VDUT and GND pins (pin 6 and pin 8) to issue commands to the INA231 chip.
Table 2-1. Signal Definition of J1 on INA231EVM Board
PIN ON J1 SIGNAL DESCRIPTION
1 I2C_SCL I2C Clock Signal (SCL)
2 CTRL/MEAS4 GPIO: Control Output or Measure
Input
3 I2C_SDA1 I2C Data Signal (SDA)
4 CTRL/MEAS5 GPIO: Control Output or Measure
Input
5 SPI_DOUT1 SPI Data Output (MOSI)
6 VDUT Switchable DUT Power Supply: +3.3
V, +5 V, Hi-Z (Disconnected)(1)
7 SPI_CLK SPI Clock Signal (SCLK)
8 GND Power Return (GND)
9 SPI_CS1 SPI Chip Select Signal ( CS)
10 SPI_DIN1 SPI Data Input (MISO)
(1) When VDUT is Hi-Z, all digital I/O are Hi-Z as well.
2.2.1 Theory of Operation for SM-USB-DIG Platform
Figure 2-3 shows the block diagram for the SM-USB-DIG Platform. This platform is a general-purpose data
acquisition system that is used on other Texas Instruments evaluation modules. The details of its operation
are included in a separate document, SBOU098 (available for download at www.ti.com). The block diagram
shown in Figure 2-3 gives a brief overview of the platform. The TUSB3210 is the primary control device for the
SM-USB-DIG Platform.
The TUSB3210 is an 8052 microcontroller that has an onboard USB interface. The microcontroller receives
information from the host computer and interprets the information into power, I2C, SPI, and other digital I/O
patterns. During the digital I/O transaction, the microcontroller reads the response of any device connected to
the I/O interface. The response from the device is sent back to the PC where the information is interpreted by the
host computer.
TUSB32108052
Microcontroller
with USB Interface
and UART
USB Bus
from Computer
3.3-V
Regulator
+3.3 V
USB
+5.0 V
8-K 8-Byte
EEPROM
´
Buffers and
Level
Translators
Power
Switching
Vdut
(Hi-Z, 3.3V or 5V)
Switched Power
I C
SPI
Control Bits
Measure Bits
2
Power-On
Reset
SM-USB-DIG
To Test Board
To Computer
and Power Supplies
+3.3 V
USB +5.0 V
Figure 2-3. SM-USB-DIG Platform Block Diagram
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3 INA231EVM (Rev A) Hardware Setup
The INA231EVM (Rev A) hardware setup involves connecting the two PCBs of the EVM together, applying
power, connecting the USB cable, and setting the jumpers. This section details this procedure.
3.1 Electrostatic Discharge Warning
CAUTION
Many of the components on the INA231EVM are susceptible to damage by electrostatic discharge
(ESD). Customers are advised to observe proper ESD handling precautions when unpacking and
handling the EVM, including the use of a grounded wrist strap at an approved ESD workstation.
3.2 Connecting the Hardware
To set up the INA231EVM and connect the two PCBs of the EVM together (that is, the INA231 Test Board
and SM-USB-DIG Platform board), gently slide the plug and socket ends of the 10-pin connectors together.
Make sure that the two connectors are completely pushed together; loose connections may cause intermittent
operation.
3.3 Connecting Power
After the EVM and SM-USB-DIG are connected, make the desired VBUS and shunt connections. Typically, setup
involves a high- or low-side load and a shunt resistor across VIN+ and VIN–. The setup in Figure 3-1 represents
a test scenario with a low-side shunt attached. This source for VBUS is not included with the kit, and the voltage
may differ depending on your testing needs. The external power source is connected to the terminal strip T3.
Note
It is always necessary to connect the power to the SM-USB-DIG Platform board before connecting the
USB cable.
Figure 3-1. Typical Hardware Test Connections for the INA231EVM
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3.4 Connecting the USB Cable to the SM-USB-DIG Platform
After power is connected, the computer typically responds with a Found New Hardware, USB Device pop-up
dialog. The pop-up window typically changes to Found New Hardware, USB Human Interface Device. This
pop-up indicates that the device is ready for use. The SM-USB-DIG Platform uses the human interface device
drivers that are part of the Microsoft® Windows® operating system.
Figure 3-2. Connecting the USB Cable to the SM-USB-DIG Platform
In some cases, the Windows Add Hardware Wizard may pop up. If this prompt appears, click Yes to let the
system device manager install the human interface drivers. Windows then confirms installation of the drivers with
the message shown in Figure 3-3.
Figure 3-3. Confirmation of SM-USB-DIG Platform Driver Installation
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3.5 INA231EVM Default Jumper Settings
Figure 3-4 shows the default jumper configuration for the INA231EVM. In general, the jumper settings of the
SM-USB-DIG Platform do not need to be changed. Users may want to change some of the jumpers on the
INA231EVM board to match their specific configurations. For example, user can set a specific I2C address by
configuring J3-J6.
Figure 3-4. INA231EVM Default Jumper Settings
Typically, jumper 2 on the INA231EVM is always set to the INT position. When set to the INT position, the
SM-USB-DIG Platform provides the supply for the INA231. When this jumper is set to the EXT position, an
external supply voltage can be connected to terminal strip T2 to provide the supply for the INA231.
Jumpers 3 through 6 control the I2C address pins for the INA231. These jumpers can set the address for A0 and
A1 to either supply, ground, SCL, or SDA. Make sure to only connect one jumper at a time for each address
control. Failure to properly connect jumpers can cause shorts or interruptions in the communication lines. See
also the INA231 data sheet.
Table 3-1 summarizes the function of the INA231 Test Board jumpers. For most applications, all jumpers should
be left in the respective default configurations.
Table 3-1. INA231EVM Test Board Jumper Functions
JUMPER DEFAULT PURPOSE
J2 INT This jumper selects whether the VS pin on the INA231 is connected to the VDUT signal generated from the SM-USB-
DIG Platform or whether the digital supply pin is connected to terminal T2, allowing for an external supply to power
the device. The default INT position connects the VS pin to the VDUT control signal.
J3/J4 GND This jumper selects the I2C A0 address selection for A0.
J5/J6 GND This jumper selects the I2C A1 address selection for A1.
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3.6 INA231EVM Features
This section describes some of the hardware features present on the INA231EVM test board.
3.6.1 J2: I2C VS Control Setting
Users can connect voltage signals to the INA231 supply pin through Jumper J2. If J2 is set to the INT position,
the VS pin is connected to the switchable VDUT signal generated from the SM-USB-DIG Platform. This voltage
can be set to either 3.3 V or 5 V, depending on how it is configured in the software. While J4 is set in the INT
position, the VS Power button in the INA231EVM software is able to control whether the VDUT supply voltage is
turned on or off.
When J2 is set in the EXT position, an external supply connected to terminal T2 can be used to provide the
supply voltage for the INA231.
3.6.2 J3 and J4: I2C Address Hardware Setting (A0)
Jumpers J3 and J4 are used to set the hardware setting for the A0 I2C address pin on the INA231. Through J3,
the user can set the A0 address to either a logic '1' or a logic '0'. Through J4, the user can set the A0 to either
the SCL or SDA communication line. Make sure to only have either J3 or J4 connected individually; failure to
keep these lines separate can lead to board shorts and problems with the I2C communication lines. See Section
5.2.1 on how to configure the INA231EVM software to match the J3/J4 hardware setting.
3.6.3 J5 and J6: I2C Address Hardware Setting (A1)
Jumpers J5 and J6 are used to set the hardware setting for the A1 I2C address pin on the INA231. Through J3,
the user can set the A1 address to either a logic '1' or a logic '0'. Through J4, the user can set the A1 address
to either the SCL or SDA communication line. Make sure to only have either J5 or J6 connected individually;
failure to keep these lines separate can lead to board shorts and problems with the I2C communication lines.
See Section 5.2.1 on how to configure the INA231EVM software to match the J5/J6 hardware setting.
3.6.4 External I2C Lines and Terminal Block T1
The I2C communication lines on the INA231EVM are tied to two sources: the internal I2C communication lines
from the SM-USB-DIG and the terminal block T1. If the user wants to add external signals separate from the
SM-USB-DIG, simply disconnect the SM-USB-DIG from the INA231EVM board and hook up the necessary SDA,
SCL, and GND lines. Also, remember to apply an external supply to the lines that is compatible with the I2C
communication device being used.
Note
Failure to disconnect the SM-USB-DIG while using external I2C communication can cause damage to
the SM-USB-DIG or any external communication devices that are connected.
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3.6.5 VIN+ and VIN– Input filter (R1, R2, and C1)
The INA231EVM has an optional input filter to remove high-frequency noise from the inputs VIN+ and VIN–. The
default values for R1 and R2 are 0 Ω. Figure 3-5 shows the typical setup that TI recommends for basic INA231
evaluation.
Figure 3-5. Typical Filter Setup
3.6.6 Shunt Monitor Configuration and Terminal Blocks T3 and T4
The INA231 is generally used in either a high-side or low-side shunt configuration, as shown in Figure 3-6.
Terminal block T3 represents VBUS and ground, while terminal block T4 represents VIN+ and VIN–. Depending
on the user’s needs, either of these configurations may be used without making any changes to the INA231EVM
board or software.
GND
BUS
V
I
High-Side
Shunt
Low-Side
Shunt
Load
Power Supply
(0 V to 28 V)
VIN+
VIN-
Figure 3-6. INA231 Shunt Configurations
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4 INA231EVM Software Setup
This section discusses how to install the INA231EVM software.
4.1 Operating Systems for the INA231EVM Software
The INA231EVM software has been tested on Microsoft® Windows® XP operating systems (OS) with United
States and European regional settings. The software should also function on other Windows OS platforms.
4.2 Software Installation
The INA231EVM software is included on the CD that is shipped with the EVM kit. The software is also available
through the INA231EVM product folder on www.ti.com. To install the software to a computer, insert the disc into
an available CD-ROM drive. Navigate to the drive contents and open theINA231EVM software folder. Locate the
compressed file (INA231EVM.zip) and open it using WinZIP® or a similar file compression program; extract the
INA231EVM files into a specific INA231EVM folder (for example, C:\INA231EVM) on your hard drive.
After the files are extracted, navigate to the INA231EVM folder created on the hard drive. Locate the setup.exe
file and execute it to start the installation. The INA231 software installer file then begins the installation process
as shown in Figure 4-1.
Figure 4-1. INA231EVM Software Installation
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After the installation process initializes, the user is given the choice of selecting the directory in which to
install the program; the default location is C:\Program Files\INA231\ and C:\Program Files\National Instruments\.
Following this option, two license agreements are presented that must be accepted, as shown in Figure 4-2.
After accepting the Texas Instruments and National Instruments license agreements, the progress bar opens and
shows the installation of the software (see Figure 4-3). When the installation process is complete, click Finish.
Figure 4-2. INA231EVM License Agreements
Figure 4-3. INA231EVM Software Installation Progress
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5 INA231EVM Software Overview
This section discusses how to use the INA231EVM software. Software operation involves a two-step process:
configuration of the INA231 settings and operation of the tool.
5.1 Starting the INA231EVM Software
Users can operate the INA231 software through the Windows Start menu. From Start, select All Programs; then
select the INA231EVM program.
Figure 5-1 shows how the software will appear if the INA231EVM is functioning properly.
Figure 5-1. INA231EVM Software Interface
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Figure 5-2 shows an error that pops up if the computer cannot communicate with the EVM. If you receive this
error, first check to see that the USB cable is properly connected on both ends. This error can also occur if
you connect the USB cable before the SM-USB-DIG Platform power source. Another reason for this error is
that there may be an issue with the computer USB Human Interface Device Driver. Make sure that the device
is recognized when the USB cable is plugged in; recognition is indicated by a Windows-generated confirmation
sound.
Figure 5-2. INA231EVM Software: Communication Error with the SM-USB-DIG Platform
5.2 Configuring the INA231EVM Software
The INA231EVM software first requires a series of setup processes to configure the device and ensure that the
device works properly. On the Configuration tab (see Figure 5-1), there are six steps noted:
1. Set I2C Address
2. Configure Operation
3. Set Conversion Times
4. Select Configuration Method
5. Set Configuration Register
6. Configure Alert Pin
This section explains how to configure the software and reviews some of the different setups that can be done.
5.2.1 I2C Address Selection
The INA231 device has a flexible I2C address configuration that allows multiple devices on the same I2C lines.
By moving the A0 and A1 addresses on jumpers J3-J6 to either GND, VS, SDA or SCL, the user can change the
INA231to a total of 16 I2C addresses (see Table 5-1).
Table 5-1. INA231 I2C Address Configuration
A1 A0 TARGET ADDRESS
GND GND 1000000
GND VS+ 1000001
GND SDA 1000010
GND SCL 1000011
VS+ GND 1000100
VS+ VS+ 1000101
VS+ SDA 1000110
VS+ SCL 1000111
SDA GND 1001000
SDA VS+ 1001001
SDA SDA 1001010
SDA SCL 1001011
SCL GND 1001100
SCL VS+ 1001101
SCL SDA 1001110
SCL SCL 1001111
Figure 5-3 shows how to configure the I2C addresses. Click the A0 or A1 box and select how to configure the
hardware on the EVM. Failure to select the correct address prevents the INA231 device from communicating
with the software.
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Figure 5-3. Setting the A1 Address
5.2.2 Configure Operating Mode
The second step of the INA231EVM configuration process allows the user to set the operating mode and the
averaging mode.
The operating mode allows the user to restrict the amount of calculations done within the INA231 by changing
the conversion to be triggered or continuous, or by shutting down the part altogether. When the device is
operating in triggered mode, the device only performs conversions when the operating mode is set and the Write
All Reg button at the top of the screen is selected. After the mode changes and Write All Reg is selected, the
user must select the Read All Reg button to see the changes on the device reflected in the software.
When the INA231 is operating in continuous mode, conversions are performed directly after the previous
conversion is complete. When the INA231EVM software is in continuous mode, the user can click the Read All
Reg button to update the software at any time.
Power-down mode stops all conversions from taking place until the operating mode changes again. The device
remains attached to power but draws minimal current and does not perform any conversions.
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All three operating modes can also be limited to only measuring certain components of the device, as shown
in Figure 5-4. It is important to note that for complete functionality of the INA231, the user must choose a
configuration with Shunt and Bus configuration. Failure to choose Shunt and Bus configuration disables a
considerable portion of the unit functionality as discussed in the INA231 data sheet.
Figure 5-4. Configuring Operating Mode
The Configure Operation step also contains a drop-down box to select Averaging Mode. The user can set up
the INA231 to take the average of several measurements before storing the value of the measurements in the
register table.
5.2.3 Set Conversion Times
Setting the conversion times allows the user to customize the amount of measurement time for conversions.
Typically, for the INA231EVM software, the user is not able to notice a visual difference between the conversion
times unless a high averaging mode and conversion time are chosen. Figure 5-5 shows the Shunt and Bus
conversion times.
Figure 5-5. Configuring Conversion Times
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5.2.4 Set Configuration Register
The user must set the Configuration Register correctly for the software to operate properly. There are two
methods used to set the Configuration Register: first, the user can manually calculate the desired value and then
input that value into the register table, as shown in Equation 1. Alternatively, the user can allow the software
to create a recommended window and choose an LSB for the current as shown in Figure 5-7. Both methods
accomplish the same goal by using Equation 1, but the method is selected by changing the value in Step 4:
Select Configuration Method (as Figure 5-6 and Figure 5-7 show).
Calibration Register = 0.00512
Current R
LSB SHUNT
´
(1)
The current LSB is calculated by a recommended range in the INA231 data sheet as shown in Equation 2. It is
important to note that with either of the methods used, the Current LSB and the Calibration Register values are
calculated based on the other variable and the RSHUNT value. See the section Programming the INA231 in the
product data sheet for more information on setting the Calibration Register value.
Max Expected Current
215
Max Expected Current
212
£CurrentLSB £
(2)
Figure 5-6. Setting the Configuration Register
(Calibration Register)
Figure 5-7. Setting the Configuration Register
(Current LSB)
5.2.5 Configuring the Alert Pin
The Alert Pin from the INA231 allows the user to set limits that monitor the registers and trigger a flag when they
are exceeded. The user can change the register that is monitored by selecting the desired alert configuration as
shown in Figure 5-8. The value considered is compared to the Alert Limit box. This Alert Limit box modifies the
functionality based on the selected configuration. It is important to note that the INA231 Alert pin is set to active
low by default.
Figure 5-8. Configuring the Alert Pin
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In addition to the INA231EVM software alert configuration, the Alert Configuration box includes the Conversion
Ready button that allows for a special functionality on the Alert pin. When the INA231 completes the conversions
for its current operation, the device triggers the Alert pin and notifies the user that another conversion can be
performed. In most cases, the INA231 conversion ready flag is not visible because of the speed of the INA231
conversion process.
5.3 Using the INA231EVM Software
After configuring the INA231EVM software, the rest of the tabs can be evaluated. This section describes the
basic operation of the device, and offers guidelines for interpreting the graphic user interface (GUI).
5.3.1 INA231 Bus Voltage, Shunt Voltage, Current, and Power Reading Bar
The bottom bar of the INA231 software, as shown in Figure 5-9, allows the user to constantly check the status
of the INA231 unit itself. These values are updated each time the user clicks the Read All Reg button at the top
of the software. In addition to the register values stored in the part, the software also includes flags for when the
part is ready to trigger another conversion and when the Alert pin is triggered.
Figure 5-9. INA231 Results Bar
5.3.2 Calculation and Theory of Operation
The Calculation tab, as shown in Figure 5-10, allows the user to follow the software flow with basic calculations
performed from within the device. It is important to note that the calculations are performed with the decimal
values of the corresponding registers.
Figure 5-10. Theory of Operation Flowchart on the Calculation Tab
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5.3.3 Register Tab
The Register tab contains information on the individual operation of the INA231 registers. Each register can be
changed on a bit-by-bit basis to allow the user to have total control of the device beyond the general functionality
of the GUI alone. Most of this functionality is displayed in the Configuration register tab, but by selecting the
appropriate register and clicking the Help With Reg button on the Register tab, as shown in Figure 5-11, the user
can diagnose the individual uses of each bit in each register.
Figure 5-11. Registers Tab
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5.3.4 Graph Tab
The Graph tab contains a plot window that shows the progression of data over time on the INA231. All four
variables at the bottom of the EVM software (VBUS, VSHUNT, Current, and Power) can be plotted using the
drop-down box directly above the graph. After the desired plot has been selected, toggle the Continuously Poll
Data button above the plot to begin polling for data. If the user desires to save the data from the plot, simply
select the USB Controls drop-down at the top of the page, then select the Start Graph Log option. When the
Start Graph Log is selected, the user is prompted to select a location for the data and to name the file.
Figure 5-12. Graphing the INA231 Data
5.3.5 Auto-Write and the Supply Voltage
The INA231EVM software allows users to customize the board level voltage, regulated by the SM-USB-DIG. By
selecting either 3.3 V or 5 V, the user can designate the operating voltage of the device.
The software also includes an Auto-Write feature shown in Figure 5-13, which is enabled by default. This feature
automatically updates the register table whenever a change is made. When this feature is enabled, the Write All
Registers button serves little purpose and is only used as an alternative to when Auto-Write is disabled.
Figure 5-13. Auto-Write, Power Button, and Voltage Control
INA231EVM Software Overview www.ti.com
20 INA231EVM (Rev A) SBOU128A – FEBRUARY 2013 – REVISED MARCH 2023
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Copyright © 2023 Texas Instruments Incorporated